General regression

[delvedor]

After some test I saw a general regression in the benchmarks.
Both in Node v4 and v6.

The bench:

JSON.stringify array x 3,796 ops/sec ±0.83% (92 runs sampled)
fast-json-stringify array x 1,629 ops/sec ±1.20% (90 runs sampled)

JSON.stringify long string x 13,905 ops/sec ±0.75% (93 runs sampled)
fast-json-stringify long string x 13,805 ops/sec ±0.86% (91 runs sampled)

JSON.stringify short string x 5,121,081 ops/sec ±0.90% (88 runs sampled)
fast-json-stringify short string x 4,957,411 ops/sec ±0.85% (90 runs sampled)

JSON.stringify obj x 1,814,632 ops/sec ±0.93% (87 runs sampled)
fast-json-stringify obj x 1,583,802 ops/sec ±0.79% (92 runs sampled)

I'll do more test.
Related: fastify/fastify#34

[mcollina]

The cultprit is 1a63b7c